Generally, the Digital Visual Interface (DVI) standard is known as the connection standard of personal computers and displays, and the High-Definition Multimedia Interface (HDMI) standard, for example, is known as the interface standard between audiovisual apparatuses. It is disclosed by, for example, Jpn. Pat. Appln. KOKAI Publication Nos. 2006-310197 and 2008-72419. The HDMI standard is obtained by improving the DVI standard having a video transmission function by, e.g., adding an audio transmission function.
An HDMI cable complying with the HDMI standard is used as it is connected to a transmitter and receiver. The HDMI cable includes a Transition Minimized Differential Signaling (TMDS) transmission unit, +5V-power transmission unit, Hot Plug Detect (HPD) signal line, Extended Display Identification Data (EDID) signal transmission unit, and Consumer Electronics Control (CEC) signal line.
The TMDS signal transmission unit transmits a video signal containing a video component and audio component from the transmitter to the receiver. The +5V-power transmission line applies a voltage of +5 V from the transmitter to the receiver when the HDMI cable is connected to the transmitter and receiver. This notifies the receiver that the HDMI cable is connected to the transmitter and receiver. The HPD signal line transmits, from the receiver to the transmitter, an HPD signal indicating that the receiver is ready for the reception of a video signal. The EDID signal transmission unit bidirectionally transmits an EDID signal between the transmitter and receiver. Accordingly, authentication can be performed between the transmitter and receiver. The CEC signal line bidirectionally transmits a CEC signal between the transmitter and receiver. This makes it possible to control the whole system.
The above-mentioned HDMI cable uni-directionally transmits a video signal from the transmitter to the receiver. When transmitting a video signal at the HDMI cable by using, e.g., optical fibers normally capable of transmitting signals only uni-directionally, no video signal can be transmitted from the transmitter to the receiver if the HDMI cable is reversely connected to the transmitter and receiver. Therefore, demands have arisen for a cable capable of detecting the transmission direction of a video signal and performing processing in accordance with the detected video signal transmission direction.